1. Field of the Invention
This invention relates generally to liquid metal cooled nuclear reactors, particularly to equipment for handling nuclear fuel assemblies, and more particularly to an apparatus for isolating a particular reactor core position for easy insertion and withdrawal of fuel assemblies at that position.
2. Description of the Prior Art
In any nuclear reaction which is intended to operate over an extended period of time, such as a reactor which is to be utilized for the generation of electrical power, the reactor facility should be constructed for removal and disposal of used or "spent" fuel elements and for recharging or refueling of the reactor with new or unused fuel elements.
One particular problem which has been encountered with sodium-cooled fast reactors has been accurately locating the fuel subassembly to be removed.
This problem comes about because of the relatively small size of the typical fuel assembly and the tight packing of these assemblies within the core region. It is further compounded by the fact that sodium is not transparent and thus the assemblies cannot be visually located.
Another problem brought about by the tight packing of the fuel assemblies in the core is that of preventing the accidental withdrawal of adjacent assemblies when a desired assembly is being pulled from the core. Also, again due to the tight packing it is desirable to have some means for maintaining the core positions, from which an assembly has been withdrawn, open to facilitate the inserting of a new assembly in its place.